Abstract: A process for making a hydraulic cementitious mixture, which process comprises the steps of: (i) providing a first granular composition (A) comprising expressed in terms of weight percent on an oxide basis: SiO2 55 to 80, Al2O3 10 to 20, Na2O 1 to 10, K2O 1 to 10, Fe2O3 0.5 to 2, SrO 0 to 7, BaO 0 to 7, Ce2O3 0 to 4,CaO 0 to 2, La2O3 0 to 2, Nd2O3 0 to 1, Pr2O3 0 to 0.5, P2O5 0 to 0.5, ZrO2 0 to 0.5, Sb2O3 0 to 0.5, TiO20 to 0.5, MgO 0 to 0.2, MnO 0 to 0.1, wherein the chloride ion content is from 0.013 to 0.05 weight % and the sulphate ion content is from 0.03 to 0.15 weight %, and (ii) providing a second granular composition (B) comprising expressed in terms of weight percent on an oxide basis: CaO 80 to 99, SiO2 1 to 10, Fe2O30.1 to 1.5, MgO 0 to 8, Al2O3 0 to 3, BaO 0 to 2, K2O 0 to 0.4, Na2O 0 to 0.2, SrO 0 to 0.2, MnO 0 to 0.2, Ce2O30 to 0.1, La2O3 0 to 0.1, Pr2O3O 0 to 0.1, P2O5 0 to 0.1, Nd2O3 0 to 0.1, TiO2 0 to 0.1, wherein the chloride ion content is from 0.001 to 0.